Dimeric liquid crystalline thermosets from azo-containing diglycidyl ether cured by anhydride

A series of dimeric liquid crystalline (LC) epoxy monomers containing azobenzene group with central spacers of different lengths were synthesized and structurally characterized by 1 H NMR, 13 C NMR, and elemental analysis. The mesogenic behavior of these monomers was measured by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction (XRD). Like other dimeric LC epoxy monomers, the melting points, clear points, and mesophase of these compounds are influenced by the carbon numbers of central spacers. Anhydride was employed to cure the monomers and LCTs with nematic phase were obtained. Thermal properties, dynamic mechanical properties and UV–Vis spectra of the LCTs were studied. The decomposition of the LCTs occurred near 220 °C and followed three stages. The LCTs also had the natural absorbance bonds of azo compounds.